This is due to libintl.h NOT including locale.h when not building at least at -O1, see http://blog.flameeyes.eu/2008/09/02/testing-the-corner-cases for more information about the problem.
Created attachment 167303 [details] Build log
%% CFLAGS="$(portageq envvar CFLAGS) -O0" ebuild rotix-0.83.ebuild install clean %% echo $? 0 Can't reproduce.
Add USE=nls.
Created attachment 238919 [details] Patch for rotix.c
Created attachment 238921 [details] New ebuild
Created attachment 238923 [details] Ebuild diff
+ 16 Jul 2010; Markos Chandras <hwoarang@gentoo.org> + files/0.83-respect-CFLAGS-and-dont-strip.patch, rotix-0.83.ebuild, + +files/rotix-0.83-locale.diff: + Apply patch from Dane Smith <smithdanea@gmail.com> to fix compilation + problems with USE=nls and -O0. Bug #239964. Respect LDFLAGS and drop + custom CFLAGS for debug mode +